434 PROF. T. H. HUXLEY ON STAGONOLEPIS ROBERTSONI, 



I was thus enabled to assure myself that the rectification of Prof. 

 Plieninger's interpretation of the bone which he terms the ischium, 

 upon which I had ventured (I. c. p. 40), was fully justified. It is, 

 in fact, the ankylosed scapula and coracoid. Both the humeri are 

 preserved, and they are about two thirds the length of the femora. 

 The femora resemble those of Megalosaurus. They have a strong 

 inner trochanter ; and there is a ridge upon the posterior face of the 

 outer condyle. The tibia has a strong cnemial ridge, though the 

 latter is not so prominent as in Megalosaurus. The left tibia and 

 fibula, lacking their proximal ends, are preserved in almost their 

 natural relations. The tibia could not have been more than three 

 or four inches shorter than the femur ; and its distal end is very 

 like that of Megalosaurus. The fibula is a strong bone, its shaft 

 being about half the diameter of the tibia. About half the astra- 

 galus is in place at the distal end of this tibia. It has the charac- 

 teristic concavo-convex form; but its outer moiety is broken away. 

 A rudiment of the ascending process is traceable ; whether it has 

 been broken or not is not clear. The left foot has been dislocated 

 backwards. The proximal ends of three large separate metatarsals 

 lie side by side; and close to them are two distal tarsal ossicles. 

 There appear to have been four (if not five) digits. 



It is unquestionable that Zanclodon is very nearly allied to 

 Megalosaurus ; and if, as I think there is little reason to doubt, the 

 fossil named by von Meyer Teratosaurus, is the jaw of Zanclodon, 

 the affinity is exceedingly close*. Inasmuch as the sacrum is com- 

 posed of a smaller number of vertebree than in Megalosaurus, it may 

 be said that Zanclodon is a less differentiated form; but in the 

 absence of a sufficiently complete knowledge of the ventral elements 

 of the pelvis and of the skull, it would be hardly safe to come to 

 any decided conclusion on this point. 



At p. 44 of the ' Memoir on the Triassic Dinosauria,' to which 

 reference has already been made, I have discussed the characters of 

 the Thecodontosauria, and have shown grounds for arranging them 

 among the Ornithoscelida. On one point I wish to make a cor- 

 rection. Acquaintance with the ilium of Stagonolepis convinces 

 me that I have turned the ilium of the Thecodontosauria the wrong 

 way — that what I have termed its anterior end is its posterior end, 

 and vice versa. The importance of this fact is that the ilium of 

 Thecodontosaurus f , thus regarded, instead of being more especially 

 Ornithoscelidan than that of Megalosaurus, is in reality much more 



* I carefully examined the wonderful bone which Plieninger has considered to 

 be a sternum ; and Herr Kapff was good enough to show me a fossil representing 

 half a smaller example of the same bone. Plausible as Plieninger's interpretation 

 appears at first sight, I must withdraw my assent to it. The large antero- 

 lateral processes which he figures end, in front, in smooth concave faces, as if 

 they had formed part of a large articular cavity, while at their dorsal and 

 ventral extremities they are rough, as if they had articulated with other bones. 

 'I he resemblance of these to the pleurosteal processes of the bird's sternum, 

 suggested in my paper, does not hold when they are closely examined. I am 

 much inclined to think that the great shield may represent coalesced ischia. 



t I use this name without being able to say whether the bones in question 

 belonged really to Thecodontosaurus or to Palceosaurus (I. c. p. 45). 



